He Xun, Shu Xiaoyong, Zhou Ziyi, Yang Shouhua, You Limei, Peng Xiao
School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China.
Jiangxi Provincial Engineering Research Center for Surface Technology of Aeronautical Materials, Nanchang Hangkong University, Nanchang 330063, China.
Materials (Basel). 2023 Nov 17;16(22):7205. doi: 10.3390/ma16227205.
The oxidation of β-NiAl at high temperatures leads to the preferential formation of metastable alumina, such as θ-AlO, which exhibits a significantly faster growth rate compared to stable α-AlO. However, our recent research has shown that through the use of the surface-dispersing nanoparticles (NPs) of metal oxides with a hexagonal closed pack (hcp), such as α-AlO, the thermal growth of α-AlO can be facilitated. The present study employed laser additive manufacturing (LAM) to develop an integrated α-AlO NPs surface-seeded two-phase intermetallic alloy comprising brittle β-NiAl and tougher γ'-NiAl, which demonstrated better comprehensive mechanical properties. It was found that seeding the α-AlO NPs promoted the early stage growth of α-AlO on both β and γ' phases during oxidation in air at 1000 °C. This led to a decrease in the oxidation rate but an enhancement in adhesion of the formed alumina scale in comparison to the naked β/γ' two-phase alloy. The reasons for this result were interpreted.
β-NiAl在高温下的氧化会导致优先形成亚稳氧化铝，如θ-AlO，与稳定的α-AlO相比，其生长速率显著更快。然而，我们最近的研究表明，通过使用具有六方密堆积（hcp）结构的金属氧化物表面分散纳米颗粒（NPs），如α-AlO，可以促进α-AlO的热生长。本研究采用激光增材制造（LAM）技术，开发了一种集成了α-AlO NPs表面籽晶的两相金属间合金，该合金由脆性的β-NiAl和韧性更强的γ'-NiAl组成，具有更好的综合力学性能。研究发现，在1000℃空气中氧化过程中，α-AlO NPs的籽晶促进了α-AlO在β相和γ'相上的早期生长。与裸露的β/γ'两相合金相比，这导致氧化速率降低，但形成的氧化铝膜的附着力增强。对这一结果的原因进行了解释。
